1. Field of the Invention
This invention relates broadly to surgical devices. More particularly, this invention relates to a bone fixation system, and particularly to a fixation system adapted to fixate a Colles"" (or distal radial) fracture.
2. State of the Art
Referring to FIG. 1, a Colles""fracture is a fracture resulting from compressive forces being placed on the distal radius 10, and which causes backward displacement of the distal fragment 12 and radial deviation of the hand at the wrist 14. Often, a Colles"" fracture will result in multiple bone fragments 16, 18, 20 which are movable and out of alignment relative to each other. If not properly treated, such fractures result in permanent wrist deformity. It is therefore important to align the fracture and fixate the bones relative to each other so that proper healing may occur.
Alignment and fixation are typically performed by one of several methods: casting, external fixation, interosseous wiring, and plating. Casting is non-invasive, but may not be able to maintain alignment of the fracture where many bone fragments exist. Therefore, as an alternative, external fixators may be used. External fixators utilize a method known as ligamentotaxis, which provides distraction forces across the joint and permits the fracture to be aligned based upon the tension placed on the surrounding ligaments. However, while external fixators can maintain the position of the wrist bones, it may nevertheless be difficult in certain fractures to first provide the bones in proper alignment. In addition, external fixators are often not suitable for fractures resulting in multiple bone fragments. Interosseous wiring is an invasive procedure whereby screws are positioned into the various fragments and the screws are then wired together as bracing. This is a difficult and time consuming procedure. Moreover, unless the bracing is quite complex, the fracture may not be properly stabilized. Plating utilizes a stabilizing metal plate typically against the dorsal side of the bones, and a set of parallel pins extending from the plate into the holes drilled in the bone fragments to provide stabilized fixation of the fragments. However, the currently available plate systems fail to provide desirable alignment and stabilization.
It is therefore an object of the invention to provide an improved fixation and alignment system for a Colles"" fracture.
It is another object of the invention to provide a volar fixation system which desirably aligns and stabilizes multiple bone fragments in a distal radial fracture to permit proper healing.
In accord with these objects, which will be discussed in detail below, a volar fixation system is provided which generally includes a T-shaped plate intended to be positioned against the volar side of the radial bone, a plurality of bone screws for securing the plate along a non-fractured portion of the radial bone, and a plurality of bone pegs which extend from the plate and into bone fragments of a Colles"" fracture.
The plate is generally a T-shaped plate defining an elongate body, a head portion angled relative to the body, a first side which is intended to contact the bone, and a second side opposite the first side. The body portion includes a plurality of countersunk screw holes for the extension of the bone screws therethrough. The head portion includes a plurality of threaded peg holes for receiving the pegs therethrough. According to a first embodiment, the peg holes are preferably non-linearly arranged. According to a second embodiment, the peg holes are preferably linearly arranged. In either embodiment, the peg holes are positioned increasingly distal in a medial to lateral direction along the second side. According to a preferred aspect of the invention, axes through the holes are oblique relative to each other, and are preferably angled relative to each other in two dimensions. The pegs having a threaded head and a relatively smooth cylindrical shaft.
The system preferably also includes a guide plate which temporarily sits on top of the volar plate and includes holes oriented according to the axes of the peg holes for guiding a drill into the bone fragments at the required orientation. The volar plate and guide plate are also preferably provided with mating elements to temporarily stabilize the guide plate on the volar plate during the hole drilling process.
In use, the volar plate is positioned with its first side against the volar side of the radius and bone screws are inserted through the bone screw holes into the radius to secure the volar plate to the radius. The bone fragments are then aligned and the guide plate is positioned on the second side of the volar plate. A drill, guided by guide holes in the guide plate, drills holes into the bone fragments, and the guide plate is then removed.
The pegs are then inserted through the peg holes and into the holes in the bone, and the heads of the pegs are threadably engaged in the volar plate. The volar fixation system thereby secures the bone fragments in their proper orientation.
Additional objects and advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description taken in conjunction with the provided figures.